Pump assembly

ABSTRACT

A dual pump apparatus for use on a vehicle or industrial application having a housing in which a pair of hydraulic pumps are mounted and driven by a prime mover. The prime mover is drivingly coupled to a main input shaft, which drives the hydraulic pumps. An auxiliary pump may be drivingly coupled to the main drive shaft and a power take off unit may also be connected thereto. The power take off unit may be driven by a power take off unit output drive shaft, on which a cooling fan may be attached.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent Ser. No.10/987,681 filed on Nov. 12, 2004 and patent Ser. No. 11/020,699 filedon Dec. 23, 2004, which are incorporated herein by referenced in theirentirety.

BACKGROUND OF THE INVENTION

This application relates in general to hydrostatic pumps andtransmissions and in particular to a multi-pump arrangement. Hydrostaticpumps are well-known for use in driving vehicles such as tractors andother off-road devices. Such pumps are also used in a wide variety ofindustrial applications other than vehicles.

In one known arrangement for a vehicle, a plurality of pumps is mountedin separate housings on a vehicle frame. Each pump is connected to arespective hydrostatic motor through high pressure hoses, which areoften connected to the pump through an end cap. The end cap is securedto the pump housing and includes a running surface for the pump cylinderblock and porting to connect the cylinder block to the hoses.

A control arm is engaged to each hydrostatic pump to control the outputof the pump. In a known design, the hydrostatic pump is of an axialpiston design and the control arm is engaged to a swash plate, therotation of which can change the output of the pump from forward toneutral to reverse. Rotation of the pumps is provided by rotary inputshafts which are separately driven by the vehicle engine through pulleysand belts or other known methods. The pump transmits hydraulic fluidthrough one of a pair of high pressure hoses to a hydrostatic motor.Rotational output of the motor is then transmitted to the vehicle drivewheels through an output axle or other known means.

Such an arrangement allows for zero turn capability, since thehydrostatic pumps may be operated independently of one another. However,there is a cost involved with this arrangement, as it requires at leastfour separate housings for the individual pumps and motors, and eachhousing must be individually secured to the vehicle frame.

A BDU transmission, which is a hydrostatic transmission (“HST”) that iscurrently known in the industry, comprises a single housing enclosingboth a hydrostatic pump and a hydrostatic motor, both of which aremounted to a single plate. The pump input shaft and motor output shaftare parallel to one another, and the plate contains hydraulic porting toconnect the pump and motor. One such hydrostatic transmission is shownin U.S. Pat. No. 5,392,670. Such an HST is generally used to connect toa drive train for powering output axles of a tractor or similar vehicle.

SUMMARY OF THE INVENTION

A multi-pump apparatus for use on a vehicle or industrial applicationhaving a housing in which hydraulic pumps are mounted and driven by aprime mover is provided. The prime mover is drivingly coupled to a maininput shaft, which drives the hydraulic pumps. An auxiliary pump may bedrivingly coupled to the main drive shaft and a power take off unit mayalso be connected thereto.

A better understanding of the objects, advantages, features, propertiesand relationships of the invention will be obtained from the followingdetailed description and accompanying drawings which set forthillustrative embodiments that are indicative of the various ways inwhich the principles of the invention may be employed.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 depicts a vehicle employing a first embodiment of the driveassembly of the present invention with one drive wheel removed forclarity.

FIG. 2 is a side view of a first embodiment of this invention withcertain internal elements shown in phantom to show one type ofconnection to the prime mover.

FIG. 3 is a side view of a first embodiment of this invention withcertain internal elements shown in phantom to show another type ofconnection to the prime mover.

FIG. 4 is a side view of the external casing of a first embodiment ofthis invention.

FIG. 5 is a top view of the dual pump design shown in FIG. 4.

FIG. 6 is a cross-sectional view of the internal components of the dualpump arrangement shown in FIG. 4, along the lines 6—6 in FIG. 4, withcertain parts shown as solid, and certain system elements shownschematically.

FIG. 7 is a cross-sectional view of the end cap of a first embodiment,along the lines 7—7 in FIG. 5.

FIG. 8 is an end view of the dual pump design shown in FIG. 5 with thePTO and gear chamber cover removed.

FIG. 9 is an end view of a second embodiment of this invention with thePTO and gear chamber cover removed.

FIG. 10 is a top view of the dual pump and auxiliary pump design shownin FIG. 9.

FIG. 11 is a cross sectional view of the end cap for the embodimentshown in FIG. 10, along lines 11—11, with certain system elements shownschematically.

FIG. 12 is a cross-sectional view of an alternative end cap design forthe embodiment shown in FIG. 11.

FIG. 13 depicts a vehicle employing a third embodiment of the driveassembly of the present invention with one wheel removed for clarity.

FIG. 14 is a side view of the embodiment of the invention shown in FIG.13.

FIG. 15 is a top view of the embodiment of the invention shown in FIG.13.

FIG. 16 is a cross-sectional view of the internal components of the dualpump arrangement shown in FIG. 15 along the lines 16—16 in FIG. 15, withcertain parts shown as solid.

FIG. 17 is a cross-sectional view of the end cap shown in FIG. 16, alongthe lines 17—17 in FIG. 16.

FIG. 18 is an end view of the third embodiment of this invention withthe gear chamber cover and fan removed.

FIG. 19 depicts a vehicle employing a fourth embodiment of the driveassembly of the present invention with one wheel removed for clarity.

FIG. 20 is a side view of the fourth embodiment of this invention.

FIG. 21 is a top view of the fourth embodiment of this invention.

FIG. 22 is a cross-sectional view of the internal components of the dualpump arrangement shown in FIG. 21 along the lines 22—22 in FIG. 21, withcertain parts shown as solid.

FIG. 23 is a cross-sectional view of the end cap of the fourthembodiment, along the lines 23—23 in FIG. 20, with certain systemelements shown schematically.

FIG. 24 is a cross-sectional view of the end cap shown in FIG. 23 alongthe lines 24—24 in FIG. 23.

FIG. 25 is a vehicle employing a fifth embodiment of the drive assemblywith one wheel removed for clarity.

FIG. 26 is a side view of the fifth embodiment of this invention.

FIG. 27 is a cross-sectional view of the end cap of the fifth embodimentalong the lines 27—27 in FIG. 26, with certain system elements shownschematically.

FIG. 28 is a cross-sectional view of the end cap shown in FIG. 27 alongthe lines 28—28 in FIG. 27.

FIG. 29 is an end view of the fifth embodiment with the fan, gearchamber cover, and charge cover removed for clarity.

FIG. 30 is an interior view of the charge cover of the fifth embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS

The following is a description of the multiple embodiments of thisinvention. Where appropriate, like numerals indicate identical orsubstantially identical components, and similar numerals with adifferent initial numeral indicate similar components with certaindifferences as specified. Further, in each of the embodiments discussedherein, identical numerals followed by “a” and “b” identify elementsthat are either identical or are mirror images of each other. Therefore,for convenience, the descriptions of elements with numerals followed by“a” apply equally to elements with identical numerals followed by “b.”

A vehicle 12 employing a first embodiment of a dual pump unit 10 isshown in FIG. 1, while the external structure thereof is shown in FIGS.4 and 5. The internal structure of dual pump unit 10 is shown in FIG. 6.While the hydraulic porting of end cap 30 is shown in FIG. 7, it will beunderstood that the drawings are not to scale, and the arrangement andsizing of the components will be obvious to a person of skill in theart. The size of pumps 51 a and 51 b and the other components will bedictated primarily by the intended applications of the unit and anyrequired external dimensions.

FIG. 1 depicts a vehicle 12 incorporating a first embodiment of thepresent invention. The arrangement shown here is of a rear enginemounting, where engine 84 is mounted on vehicle frame 88, which alsosupports motors 90, mower deck 89 and other possible attachments. Axles87 extend from motors 90 and drive vehicle wheels 85.

Pump housing 20 is mounted by way of bell housing 16 to engine 84 sothat pump housing 20 is generally parallel to vehicle frame 88 and endcap 30 is perpendicular to vehicle frame 88. Attach points 18 formed ongear chamber cover 35 may also be used to secure pump apparatus 10 toframe 88 in a number of known manners. Hydraulic hoses 70 b and 72 bcarry fluid from threaded system ports 71 and 73 to respective motors90. Pump apparatus 10 is preferably located along the center line of thevehicle, i.e., along the center of the longitudinal axis of the vehicleparallel to and between members of frame 88. This location of pumpapparatus 10 simplifies the arrangement and connections of the varioushoses, linkage mechanisms and the like. One such advantage is that hoses70 and 72 may be generally symmetrical in length and routing. Thislength symmetry includes having hoses 70 of one generally identicallength and hoses 72 of a second generally identical length, or havinghoses 70 and 72 being of one generally identical length. Note that whilethe aforementioned discussion relates to the preferable positioning ofpump unit 10 on the vehicle center line, pump unit 10 may be positionedin other locations as need dictates.

Bell housing 16 is positioned between and secured to both pump unit 10and engine 84. In addition, as shown in FIG. 6, bell housing 16 forms anenclosed space 16 a covering the coupling between main drive shaft 24and engine 84. There are a variety of configurations for connecting maindrive shaft 24 to a prime mover 84 output. One such configuration isdepicted in FIG. 2, where an engine output shaft 14 is connected to acoaxially positioned main input shaft 24 by coupler 15. Another possibleconfiguration is depicted in FIG. 3, where main input shaft 24′ of pumpapparatus 10′ is connected to flywheel 13 of prime mover 84′.

Inside housing 20 is located a pump chamber (or cavity) 50 in which aremounted a first rotatable pump 51 a and a second pump 51 b, both ofwhich are rotatably mounted on their respective running surfaces 31 aand 31 b on end cap 30. End cap 30 is secured to housing 20 by fasteners32, which also secure gear chamber cover 35 to end cap 30 and whichextend through openings 36 in end cap 30 into threaded openings (notshown) in housing 20. End cap 30 acts to close off pump chamber 50.

The following discussion of pump 51 a will also apply to second pump 51b. Pump 51 a is of the axial piston design and comprises rotatablecylinder block 53 a, in which are mounted a plurality of axial stickpistons 55 a, each of which includes a piston spring 56 a therein, withcylinder block 53 a engaged to first pump shaft 25 by means of spline 44a or similar means. Pistons 55 a abut a thrust bearing 47 a mounted inswash plate 48 a. Trunnion arm 21 a interfaces with swashplate 48 athrough slider bearing 49 a. Rotation of trunnion arm 21 a thus movesswash plate 48 a and will control the direction and flow rate of theoutput of hydraulic pump 51 a. End cap 30 is preferably made ofaluminum; it should be understood that materials such as cast iron mayalso be used and a valve plate may be used in conjunction with eithermaterial.

Trunnion arm 21 a extends out from housing 20 through seal 58 a andbushing 59 a. As shown in FIG. 8, control arms 22 a and 22 b are mountedto trunnion arms 21 a and 21 b with fasteners 23 a and 23 b. Controlarms 22 a and 22 b can be engaged to various linkage mechanisms so thatpumps 51 a and 51 b can be independently controlled by a vehicleoperator. The location of trunnion arms 21 a and 21 b on opposite endsof housing 20 (corresponding to the sides of vehicle frame 88) permitsthe use of more efficient linkage systems 69.

Main drive shaft 24 is directly engaged to an engine or prime mover 84on one end and drivingly engaged to pump shafts 25 and 26, as discussedin more detail below and as shown most clearly in FIGS. 2 and 6. Fordrivingly coupling main drive shaft 24 to pump shafts 25 and 26, aplurality of gear sets may be employed, which will be discussed ingreater detail below. In this embodiment, the output of engine 84 ishorizontal with respect to the ground, as are main drive shaft 24 andpump shafts 25 and 26.

Drive shaft 24 may also extend outside gear chamber cover 35 and drive apower take off unit (“PTO”) 29. PTO 29 may assume an engaged anddisengaged position. In the engaged position, PTO shaft 29 a will becoupled to drive shaft 24 and may be used to power an output device,such as a mower deck. In the disengaged position, PTO shaft 29 a anddrive shaft 24 will not be in driving communication with one another.PTO shaft 29 a extends outside PTO 29 and, as shown in, e.g., FIGS. 1through 6, a cooling fan 19 may be mounted on PTO shaft 29 a. Therefore,when PTO 29 is engaged and drive shaft 24 is coupled to PTO shaft 29 adrive shaft 24 will supply the driving force for PTO 29 and fan 19. Itshould be noted that PTO 29 and the corresponding extension of maindrive shaft 24 through gear chamber cover 35 is optional; shaft 24 neednot extend out in such a manner, in which case gear chamber cover 35would be a solid structure on the end thereof.

PTOs are known in the art, so only minimal explanation of the functionof PTO 29 will be provided herein. PTO 29 is attached to end cap 30 by aplurality of fasteners 67. Since PTO 29 as depicted is hydraulicallycontrolled, a source of hydraulic fluid is required. In the embodimentshown in FIGS. 6 and 7, charge fluid from passage 94 a is directed tocharge gallery 95 a and then through passage 98 to passage 99, to whichis connected hydraulic line 100, shown in FIGS. 4 and 6. Line 100 isconnected to passage 102 in gear chamber cover 35. Valve 104, which isoperator controlled by one of a variety of known techniques, is used toactivate and deactivate PTO 29. Valve 104 either provides pressurizedfluid from passage 102 to PTO gallery 105, or it blocks fluid frompassage 102 from entering into gallery 105 while relieving pressure fromgallery 105. The fluid relieved from gallery 105 travels through passage106, which is either connected to gear chamber 45 or pump chamber 50 byan internal or external connection.

When valve 104 is operated to provide pressurized fluid from passage 102to gallery 105, PTO brake 107, which normally clamps PTO shaft 29 a toPTO housing 28, is deactivated, thereby leaving PTO shaft 29 a free torotate. As PTO brake 107 is being deactivated, PTO clutch 108 is beingactivated, connecting main drive shaft 24 to PTO shaft 29 a, thuscausing PTO shaft 29 a to rotate with shaft 24. When valve 104 isreturned to a deactivated position pressure is released from gallery105, allowing clutch 108 to be deactivated and brake 107 to beactivated, uncoupling PTO shaft 29 a from shaft 24 and braking PTO shaft29 a.

As shown in FIGS. 6 and 8, spur gears 52 a, 52 b and 52 c, which arepreferably helical spur gears, are mounted in gear chamber 45, which maybe sealed from pump chamber 50. Spur gear 52 c is mounted on main driveshaft 24 and is directly engaged to spur gears 52 a and 52 b, which aremounted on shaft 25 and shaft 26, respectively. Gears 52 a, 52 b, and 52c are positioned by shoulders formed on their respective shafts and byproximity to washers 54 a, 54 b and 54 c, which are located adjacentgear chamber cover 35. Shafts 25 and 26 in turn drive first and secondpumps 51 a and 51 b, respectively.

Gear chamber 45 is formed by end cap 30 and gear chamber cover 35, whichis secured to housing 20 through end cap 30 by a plurality of fasteners32, as previously noted. A sealant, gasket, or o-ring 37 may be used atthis junction to prevent leakage of hydraulic oil or gear grease. Maindrive shaft 24 may be supported and located in a variety of locations,such as PTO 29 by sealed bearing 66, housing 20 by bearing 63, end cap30 by bearing 64, or in gear chamber cover 35. Cooling fan 19 is securedto main drive shaft 24 by a spline and retaining ring (not shown) or maybe secured by a number of other known configurations. An optional oilcooler (not shown) could also be added to the system and located to takeadvantage of the air flow from cooling fan 19. A seal may be positionedadjacent main drive shaft 24 between pump chamber 50 and gear chamber 45so that different lubricants may be used in each chamber, such as oil inpump chamber 50 and grease in gear chamber 45.

As shown most clearly in FIG. 6, charge pumps 57 a and 57 b, which aregerotor style charge pumps, are mounted in end cap 30 and splined topump shafts 25 and 26. Charge pumps 57 a and 57 b may be secured in endcap 30 by charge covers 60 a and 60 b. Kidney 93 a provides oil frompassage 80 to charge pump 57 a. As shown in FIGS. 6 and 7, pressurizedoil is sent from charge pump 57 a to charge gallery 95 a through passage94 a. Charge relief opening 77 a is also formed in charge gallery 95 ato permit oil to be discharged therethrough by means of charge reliefvalve 97 a in the event of excess oil pressure.

The hydraulic porting in end cap 30 is shown in FIG. 7. System ports 71and 73 extend into end cap 30, with ports 71 a and 73 a in communicationwith first pump 51 a and ports 71 b and 73 b in communication withsecond pump 51 b. A set of check valves 101 a, 101 b, 103 a and 103 b isthreaded into respective openings 74 a and 74 b in end cap 30,corresponding to ports 71 a, 71 b, 73 a and 73 b. Check valves 101 a,101 b, 103 a and 103 b are of a standard design known in the art, andeach may include a bleed 34 formed in the end thereof. Check valves 101a and 103 a are in communication with pump 51 a, while check valves 101b and 103 b are in communication with pump 51 b.

When swash plate 48 a is in the forward position, one of ports 71 a or73 a will be under high pressure and the other port will be under lowpressure, or vacuum. When swash plate 48 a is moved to the neutralposition, neither port will be under pressure, and when the direction ofswash plate 48 a changes (e.g., from forward to reverse) the status ofports 71 a and 73 a will switch, with the formerly low pressure orvacuum side being placed under high pressure, and vice versa. The endsof each system ports 71 a, 71 b, 73 a, and 73 b are threaded to permitconnection of hoses 70 and 72 and the like.

As shown in FIG. 6, an external oil reservoir 86 may be mounted atvarious locations on vehicle 12 or on pump apparatus 10. Oil drains frompump chamber 50 through case drain 38, and then through outlet hose 91 bto reservoir 86. Oil returns to the system through inlet hose 91 a,passing through filter 92 into charge pump inlets 75 a and 75 b. Asshown in FIG. 5, case drain 38 is located in housing 20 in a locationcorresponding to pump chamber 50, so that oil will drain from chamber 50to reservoir 86 and will be passed through filter 92 before its returnto the system. Filter 92 could also be located on hose 91 b. Referringto FIG. 7, passages 80 and 81 are formed in end cap 30 and connected tocharge inlets 75 a and 75 b. The location of passages 80 and 81 betweensystem ports 71 a and 73 a allows for a compact end cap 30.

Bearing 96 a, which is preferably a standard friction bearing, is usednot only to support input shaft 25 but also to divide passage 80 intotwo separate sides, where inlet 75 a and kidney 93 a, which supplies oilfrom reservoir 86 to charge pump 57 a, are on one side thereof, andpassage 94 a, which provides pressurized oil from charge pump 57 a tocharge gallery 95 a, is on the other side. A similar bearing 96 b isalso used to support second shaft 26.

As noted above, pump chamber 50 and gear chamber 45 can be strictlysegregated, such that the hydraulic oil used in pumps 51 a and 51 b isindependent of the lubricant for spur gears 52 a, 52 b and 52 c. Thissegregation would permit the use of a gear lubricant in gear chamber 45,which may be desirable in certain applications. It should be obvious tothose with skill in the art that the foregoing arrangement may be variedwithout departing from the scope of the present invention.

A second embodiment of the present invention is shown in FIGS. 9–11. Inthis embodiment of pump apparatus 110, an auxiliary pump 157 has beenprovided in place of charge pumps 57 a and 57 b and auxiliary pump 157may provide pressure for PTO 29. As shown in FIGS. 9 and 10, auxiliarypump 157 may be positioned above main drive shaft 124 and input shafts125, 126 and attached to housing 120 by fasteners 161. The orientationof swash plates 48 a and 48 b and the location of trunnion arms 121 aand 121 b, control arms 122 a and 122 b and output system ports 171 a,171 b, 173 a and 173 b can remain generally the same as in the previousembodiment, as exemplified in FIG. 11. As shown in FIG. 9, main driveshaft 124 may be drivingly engaged to pump shafts 125, 126 and auxiliarypump shaft 127. For driving auxiliary pump shaft 127, main drive shaft124 may be coupled to gear 152 c, which transfers the driving force frommain input shaft 124 to gear 127 b, then to gear 127 a and then toauxiliary pump shaft 127. It should also be obvious to those with skillin the art that auxiliary pump 157 may also be positioned below gear 152c or may be positioned above or below shaft 125 or 126. However, theposition shown is advantageous as it allows shafts 125 and 126 to besized for the load of the pumps they drive and only shaft 124 carriesthe torque for more than one pump.

As shown in FIG. 10, trunnion arms 121 a and 121 b extend from oppositeends of housing 120. The addition of auxiliary pump 157 requires adifferent end cap 130. FIG. 11 shows a cross-section of end cap 130,taken along the lines 11—11 in FIG. 10. In this embodiment, system ports173 a and 171 a correspond to pump 51 a, and ports 171 b and 173 bcorrespond to pump 51 b.

The charge and auxiliary pump configuration of this embodiment isdifferent from that of pump apparatus 10, which does not include anauxiliary pump. Fluid is drawn from reservoir 86 through filter 92 intocharge inlet line 191 a, which is connected to charge inlet passage 181a. Passage 181 a is a portion of passage 181 that is formed through endcap 130 and then separated into charge inlet passage 181 a and chargeoutlet passage 181 b by the insertion of bearing 176.

As is known in the industry, fluid is then drawn from charge inletpassage 181 a through charge inlet kidney 193 by auxiliary pump 157,which then provides pressurized fluid through outlet passage 194 intoauxiliary outlet 181 b. Auxiliary pump 157 may be a gerotor type pump orsimilar pump. From auxiliary outlet 181 b pressurized fluid travelsthrough auxiliary line 209 a to PTO 29 or to another hydraulic auxiliarydevice 129, which may be a deck lift for deck 89, hydraulic actuatorsfor moving swash plates 48 a and 48 b, or other hydraulically operateddevices. Fluid may return from auxiliary device 129 or PTO 29 by way ofauxiliary return line 209 b. The returned fluid passes through filter183 and re-enters end cap 130 through auxiliary return inlet port 211formed in auxiliary cap 39.

Properly sized auxiliary pump 157 will provide more fluid than isnecessary to operate auxiliary device 129. To allow the excess fluid toescape the auxiliary circuit, an auxiliary relief valve 40 is providedin auxiliary relief line 41 that is connected between outlet 181 b ofauxiliary pump 157 and auxiliary return inlet port 211. A person ofskill in the art will understand that the location of auxiliary reliefvalve 40 shown is exemplary, as valve 40 may be located in a variety oflocations, including passages formed internal to end cap 130. Filter 183may similarly by located in a variety of locations, including internalto end cap 130, and in some configurations, filter 183 may not berequired.

After entry through auxiliary return inlet 211, the fluid then enters acharge fluid gallery comprising gallery 180 e, two passages 180 a and180 c extending into end cap 130, and passages 180 b and 180 d formed atright angles to passages 180 a and 180 c. Passages 180 b and 180 d aremachined or formed in end cap 130 and each is then divided into twoportions by bearings 196 a and 196 b, respectively, and the openings topassages 180 b and 180 d at the surface of end cap 130 are plugged.Gallery 180 e is preferably formed on a side of end cap 130 and closedoff by auxiliary cap 39.

Pumps 51 a and 51 b may not require all the fluid available and a chargerelief valve 197 is provided to limit the pressure in passages 180 a,180 b, 180 c, 180 d and 180 e. As shown, this relieved fluid returns toinlet 181 a of auxiliary pump 157. However, for additional cooling therelieved fluid may be returned to reservoir 86.

As shown in FIGS. 10 and 11, any fluid that escapes into the internalsump of housing 120 is returned to reservoir 86 through case drain 138and case drain line 191 b.

System ports 173 a and 173 b are also formed at a generally right angleto intersect with check plug ports 174 a and 174 b, respectively, forease of manufacture. This design permits the insertion of check plugs1101 a, 1101 b and 1103 a, 1103 b into end cap 130 in the manner shown.This arrangement keeps check plugs 111 a, 110 b and 1103 a, 1103 b awayfrom the fluid flow between pumps 51 a and 51 b and system ports 171 aand 173 a, and 171 b and 173 b, respectively. Being positioned betweenpumps 51 a and 51 b and system ports 171 and 173 would tend to reduceefficiency of pump apparatus 110. Having all of the required elementslocated in the same plane also decreases the required thickness of endcap 130.

This arrangement permits pump apparatus 110 to be mounted on vehicleframe 88 so that the axes of pumps 51 a and 51 b are parallel to thelongitudinal axis of the vehicle. This design permits main drive shaft124 to be directly driven by engine 84. This design eliminates the needfor a separate belt and pulley, which decreases costs and increases theefficiency of the unit. Reservoir 86 may be secured to pump apparatus110 or to vehicle frame 88 by a variety of known fastening mechanisms.

In this design, control arms 122 a and 122 b are mounted on the sides ofhousing 120 with respect to vehicle frame 88, which may increase theease of connection with the various linkage mechanisms 69, depending onthe structure of vehicle 12. As shown in FIG. 1, this arrangement alsosimplifies the connection of hydraulic hoses 70 and 72 from system ports171 a, 171 b, 173 a and 173 b to motors 90.

FIG. 12 shows a cross-section of another embodiment of this invention,where end cap 230 is similar in many ways to end cap 130 of FIG. 11. Inthis embodiment, a single charge pump (not shown) provides fluid topumps 51 a and 51 b. System ports 271 a and 273 a correspond to pump 51a, and ports 271 b and 273 b correspond to pump 51 b. The orientation ofswash plates 48 a, 48 b and the location of trunnion arms 21 a and 21 b,control arms 22 a and 22 b and output system ports 271 a, 271 b, 273 aand 273 b would remain similar to that of the first two embodiments.

Fluid enters the charge pump from reservoir 86 through charge inlet 281a. From inlet 281 a fluid passes through kidney-shaped opening 293 intothe charge pump. The charge pump forces fluid through passage 294 intopassage 281 b, which is also the entry into charge gallery 280. Passages281 a and 281 b are formed in a single operation and then separated bythe insertion of bearing 276 into its bore. For convenience the openingto charge relief 297 is located in passage 281 b, though it may belocated at any position where it may communicate with charge gallery280. Charge gallery 280 is formed by passage 280 a extending betweencheck plug 2103 a positioned in port 274 a and check plug 2103 bpositioned in port 274 b, and passages 280 b and 280 c are formed atright angles to passage 280 a and parallel with check plug 2101 apositioned in port 274 c and check plug 2101 b positioned in port 274 d.Passages 280 b and 280 c are then closed by plugs 233. Check plug 2103 ais connected to system port 273 a by connecting passage 42 a. Similarly,check plug 2103 b is connected to system port 273 b by connectingpassage 42 b. Connecting passages 42 a and 42 b are closed at the edgeof end cap 230 by plugs 233.

A third embodiment of the present invention is shown in FIGS. 13–18.Similar to the second embodiment of the present invention describedabove, this embodiment of pump apparatus 210 includes a main drive shaft224 drivingly engaged to pump shafts 125, 126 and auxiliary pump shaft127, which in turn drive pumps 51 a and 51 b and auxiliary pump 157,which may also be referred to as the first, second and third pumpsrespectively. The gearing connecting shafts 125, 126 and 127 (shown inFIG. 18) and the porting provided in end cap 130 (shown in FIG. 17) arealso nearly identical to the gearing and porting described in connectionwith the second embodiment and shown in FIGS. 9 and 11, and are thussimilarly numbered.

For powering a mower deck 89 or other auxiliary device a PTO assembly orPTO unit 229 may be positioned between bell housing 16 and pump housing20. This embodiment is distinguishable from the pump apparatus describedin the second embodiment and shown in FIG. 10, which discloses a PTO 29that extends from end cap 130 and that includes an output shaft that iscoaxial with the main drive shaft.

More specifically, PTO assembly 229 defines an enclosed space, which isformed by the combination of first member 229 b and plate 229 c.Assembly 229 is attached to housing 220 by fasteners 267. PTO assembly229 contains a first pulley 229 d that is selectively coupled to maindrive shaft 224 by an electric clutch 229 e. Moreover, electric clutch229 e is selectively coupled to main drive shaft 224 by key 62. Electricclutch 229 e is actuated by signals sent on electrical connector 229 j.These signals may be generated by one of a variety of methods—forexample, by operator actuation of a switch (not shown) mounted invehicle 212. Once actuated, clutch 229 e acts to selectively couplefirst pulley 229 d to main input shaft 224 by means of a hub 62 a. Otherelements are likely to be included within power take off assembly 229,such as mounting and adjusting elements 229 h. PTO 229 also includes anoutput shaft 229 a, which may be drivingly coupled to mower deck input89 a for powering mower deck 89 and which may be positioned below maindrive shaft 224. For driving output shaft 229 a, first pulley 229 d maybe drivingly coupled to a second pulley 229 f by belt 229 g. Bypositioning output shaft 229 a below main drive shaft 224, output shaft229 a and input 89 a to mower deck 89 are displaced in a substantiallycollinear relationship. It should be understood that this arrangementprovides for a more efficient transfer of power from output shaft 229 ato mower deck input 89 a and mower deck 89. Additionally, thisarrangement keeps the components associated with deck drive in alocation that provides room for other components, such as linkages andother drive line elements. It should be appreciated by those with skillin the art that electric clutches are common in the industry and thatother variations of clutches may also be used to couple first pulley 229d to main drive shaft 224.

A fourth embodiment of the present invention is shown in FIGS. 19–24. Inthis embodiment of pump apparatus 310, a hydraulic motor 329 has beenpositioned below main drive shaft 324. Motor 329, which may be a pistonmotor, a gerotor, a geroller or other design, drives output shaft 329 a,which acts as a power take off shaft. Since this embodiment allowsu-joint 362 and output shaft 329 a to be positioned in a substantiallycollinear relationship to one another, the location of motor 329 belowmain drive shaft 324 simplifies the arrangement of output shaft 329 awith respect to mower deck 89 and provides for a more efficient transferof power from motor 329 to mower deck 89. Although motor 329 is depictedas being positioned below the main drive shaft 324, motor 329 may alsobe positioned in other locations as need dictates.

Pump chamber 350 is formed in housing 320 between end cap 330 and gearchamber cover 335. A plurality of rotatable pumps, including a firstrotatable pump 351 a, a second rotatable pump 351 b (not shown), and anauxiliary pump 351 c are mounted in pump chamber 350. The two primaryrotatable pumps 351 a and 351 b operate the same as pumps 51 a and 51 b,described above, to provide output for the vehicle. Auxiliary pump 351 cpreferably operates in a similar manner, but as will be described below,the output of auxiliary pump 351 c is used to power motor 329. End cap330 may be secured to housing 320 by fasteners 332, which also securegear chamber cover 335 to end cap 330.

Trunnion arms 321 a and 321 b are located and operate similarly totrunnion arms 21 a and 21 b described above. Although trunnion arm 321 calso operates in a similar manner, it extends from the top of housing320, and control arm 322 c is mounted to trunnion arm 321 c withfastener 323. The combination of trunnion arm 321 c and control arm 322c operate to control auxiliary pump 351 c.

As exemplified in FIG. 22 and similar to pumps 51 a and 51 b describedabove, pumps 351 a and 351 b may be horizontally positioned on each sideof main drive shaft 324 and driven by pump shafts 325 and 326 (notshown), which are drivingly connected to main drive shaft 324 via aplurality of gear sets. Although the second pump 351 b is not shown inthese figures, it should be appreciated by those with skill in the artthat it is mounted on the pump mounting surface of end cap 330 in thesame manner as pump 51 b is mounted on end cap 30, which is shown inFIG. 6. For driving auxiliary pump 351 c, driving force may betransferred from main drive shaft 324 and gear 352 c to gear 327 a,where gear 327 a is also drivingly coupled to auxiliary shaft 327. Gears352 c and 327 a are preferably helical spur gears and mounted in gearchamber 345. Gear chamber 345 and pump chamber 350 operate and areformed similarly to gear chamber 45 and pump chamber 50 described above.

As shown most clearly in FIG. 22 and similar to the embodiment depictedin FIG. 6, charge pump 357, which is a gerotor style charge pump, may bemounted in end cap 330 and splined to auxiliary shaft 327. Kidney 393provides oil from passage 380 to charge pump 357. As shown in FIGS. 22and 23, pressurized oil is sent from charge pump 357 to charge gallery395 through passage 394. Charge relief opening 377 is also formed incharge gallery 395 to permit oil to be discharged therethrough by meansof charge relief valve 397 in the event of excess oil pressure. Chargepump 357 supplies charge fluid to all three rotatable pumps 351 a, b(not shown) and c, as shown in FIGS. 23 and 24.

For transferring driving force from main drive shaft 324 to output shaft329 a, end cap 330 includes hydraulic porting that connects auxiliarypump 351 c to motor 329. As depicted in FIG. 23, which is across-sectional view of end cap 330 taken along lines 23—23 of FIG. 20,system ports 371 and 373 extend into end cap 330, with ports 371 a and373 a in communication with first pump 351 a, ports 371 b and 373 b incommunication with second pump 351 b, and ports 371 c and 373 c incommunication with auxiliary pump 351 c. A set of check valves 3101 a–cand 3103 a–c may be threaded into respective openings 374 a–c and 379a–c in end cap 330, corresponding to ports 371 a–c and 373 a–c. As shownin FIG. 24, check valves 3101 a–c and 3103 a–c may be positionedsubstantially perpendicularly to the respective system ports 371 a–c and373 a–c. Check valves 3101 a and 3103 a are in communication with pump351 a, check valves 3101 b and 3103 b are in communication with pump 351b, and check valves 3101 c and 3103 c are in communication withauxiliary pump 351 c.

The pressure associated with each set of system ports 371 a, 373 a, 371b, 373 b, 371 c and 373 c will be controlled by the positioning of therespective swash plate 348 a, 348 b (not shown) or 348 c and operate inthe same manner as ports 71 a, 73 a and swash plates 48 a and 48 bdescribed above. The ends of each system ports 371 a, 371 b, 373 a, and373 b are threaded to permit connection of hoses 370 and 372 and thelike. Although system ports 371 c and 373 c are also threaded to permitconnection of hoses and the like, system ports 371 c and 373 c extendinto end cap 330 to hydraulically transfer driving force from auxiliarypump 351 c to motor 329 and output shaft 329 a, as shown in FIG. 23.

As exemplified in FIG. 23, an external oil reservoir 86 may be mountedat various locations on vehicle 312 or on pump apparatus 310. Oil maydrain from pump chamber 350 through case drain 338, and then throughoutlet hose 391 b to reservoir 86. Oil returns to the system throughinlet hose 391 a, passing through filter 92 into charge pump inlet 375.As shown in FIG. 21, case drain 338 is located in housing 320 in alocation corresponding to pump chamber 350, so that oil will drain fromchamber 350 to reservoir 86 and will be passed through filter 92 beforeits return to the system. Filter 92 could also be located on hose 391 b.Referring to FIG. 23, passage 380 is formed in end cap 330 and connectedto charge inlet 375. The operation of charge pump 357 to supply chargefluid to system ports 371 a, 371 b, 371 c, 373 a, 373 b and 373 c allowsfor a compact end cap 330.

Main drive shaft 324, pump shafts 325 and 326 (not shown), and auxiliarypump shaft 327 will operate and be supported in similar manners as maindrive shaft 24 and pump shafts 25, 26, which are described in detailabove, including using bearing 376 to support auxiliary shaft 327 anddivide passage 380 into two separate sides. As with other embodiments ofthe present invention that are described herein, a cooling fan 19 may besecured to main drive shaft 324.

A fifth further embodiment of the present invention is shown in FIGS.25–30. In this embodiment of pump apparatus 410, pump chamber 450, whichis not shown but which would be similar to previously shown pumpchambers, is formed in housing 420 and enclosed by end cap 430. Aplurality of rotatable pumps, including a first rotatable pump 451 a, asecond rotatable pump 451 b, and an auxiliary pump 451 c, which are notshown but which would be similar to previously shown pumps, are mountedin pump chamber 450. The two primary rotatable pumps 451 a and 451 boperate the same as pumps 51 a and 51 b, described above, to provideoutput for the vehicle and drive wheel motors 90. Auxiliary pump 451 cpreferably operates in a similar manner, but as will be described below,the output of the auxiliary pump 451 c is used to power motor 429. Endcap 430 may be secured to housing 420 by fasteners 432, which alsosecure gear chamber cover 435 to end cap 430.

Trunnion arms 421 a, 421 b and 421 c are not shown but would be similarto and operate similarly to trunnion arms 321 a, 321 b and 321 cdescribed above, and are positioned close to each of their respectivepumps 451 a, 451 b and 451 c. Control arms 422 a (not shown), 422 b and422 c are mounted to each respective trunnion arm 421 a, 421 b and 421 cwith fastener 423. The combination of trunnion arm 421 c and control arm422 c operate to control auxiliary pump 451 c.

As exemplified in FIGS. 26 and 27, pumps 451 a, 451 b and 451 c may bepositioned around main drive shaft 424 and driven by pump shafts 425,426 and 427, which are not shown, but which are similar to the shaftsshown in the embodiment above and which are drivingly connected to maindrive shaft 424 via a plurality of gear sets. Although it is not shownin these figures, it should be appreciated by those with skill in theart that pumps 451 a, 451 b and 451 c are mounted on the pump mountingsurface of end cap 430 in the same manner as pump 51 b is mounted on endcap 30, which is shown in FIG. 6.

For driving auxiliary pump 451 c, driving force may be transferred frommain drive shaft 424 and gear 452 c to gear 427 a, where gear 427 a isalso drivingly coupled to auxiliary shaft 427. Gears 452 c and 427 a arenot shown but are preferably helical spur gears similar to previouslyshown gears 352 c and 327 a and mounted in gear chamber 445. Gearchamber 445 and pump chamber 450 operate and are formed similarly togear chamber 45 and pump chamber 50 described above. For directlypowering mower deck 89, a hydraulic motor 429 has been positionedproximate to mower deck 89 and hydraulically connected to auxiliary pump451 c via high pressure hoses 470 c and 472 c (not shown), which will bedescribed in more detail below. Motor 429 drives output shaft 429 a andoutput shaft 429 a may act as a power take off shaft and drive mowerdeck 89. Motor 429 may be a piston motor, a gerotor, a geroller or otherdesign.

As shown most clearly in FIG. 28 and similar to the embodiment depictedin FIG. 22, charge pump 457, which is a gerotor style charge pump, maybe mounted in end cap 430 and splined to main drive shaft 424. Kidney493 provides oil from passage 480 to charge pump 457. As shown in FIGS.27–30, pressurized oil is then sent from charge pump 457 to chargegallery 495 through passage 494. Charge pump 457 supplies charge fluidto all three rotatable pumps 451 a, 451 b and 451 c through chargegallery 495 by supplying charge fluid from passage 494 to passage 495 aand then through passage 495 b to annular groove 495 c formed in chargecover 460. Charge gallery 495 is also fluidly connected to each of pumps451 a and 451 b via passages 495 e and 495 f and ports 482 a and 482 b,respectively. Charge gallery 495 may also provide charge fluid toauxiliary devices via ports 482 c and 482 d, which are connected tocharge gallery 495 c by charge passages 495 g and 495 d, respectively.Charge relief opening 477 a is also formed in passage 495 a to permitoil to be discharged therethrough by means of charge relief valve 497 ain the event of excess oil pressure. The fluid that is dischargedthrough charge relief valve 497 a enters into charge relief passage 497b and is sent to charge relief outlet 497 c formed in charge cover 460,which is in fluid connection with charge pump 457 and allows the fluidto re-enter the fluid system for the pump apparatus 410 therethrough.Note that annular groove 495 c may also be formed in end cap 430 andcharge relief passage 497 b may be formed in charge cover 460.

For transferring driving force from main drive shaft 424 to output shaft429 a, auxiliary pump 451 c and motor 429 are connected by high pressurehoses 470 c and 472 c. Further, hoses 470 c and 472 c are fluidlyconnected to system ports 471 c and 473 c on one end and at the otherend directly to motor 429. As depicted in FIG. 27, which is across-sectional view of end cap 430 taken along lines 26—26 of FIG. 26,system ports 471 and 473 extend into end cap 430, with ports 471 a and473 a being in communication with first pump 451 a, ports 471 b and 473b being in communication with second pump 451 b, and ports 471 c and 473c being in communication with auxiliary pump 451 c. A set of checkvalves 4101 a–c and 4103 a–c may be threaded into respective openings474 a–c and 479 a–c in end cap 430, corresponding to ports 471 a–c and473 a–c. As shown in FIG. 27, check valves 4101 a–c and 4103 a–c may bepositioned substantially coplanar, yet perpendicular to the respectivesystem ports 471 a–c and 473 a–c. Check valves 4101 a and 4103 a are incommunication with pump 451 a, check valves 4101 b and 4103 b are incommunication with pump 451 b, and check valves 4101 c and 4103 c are incommunication with auxiliary pump 451 c.

As with the previous embodiments and as exemplified by FIG. 27, chargepump 457 draws hydraulic fluid from reservoir 86, which may be locatedeither on vehicle 412 or on pump apparatus 410, and then through chargeinlet line 491 a and filter 92. Fluid from a case drain returns toreservoir 86 through a case drain line 491 b.

While specific embodiments of the invention have been described indetail, it will be appreciated by those skilled in the art that variousmodifications and alternatives to those details could be developed inlight of the overall teachings of the disclosure. Accordingly, theparticular arrangement disclosed is meant to be illustrative only andnot limiting as to the scope of the invention which is to be given thefull breadth of the appended claims and any equivalents thereof.

1. A pump apparatus, which is driven by a prime mover having an outputshaft, the pump apparatus comprising: a bell housing attached to theprime mover; a power take off unit attached to bell housing; a pumphousing attached to the power take off unit, the pump housing includinga first pump, a second pump and a third pump enclosed therein; a maininput shaft drivingly coupled to the prime mover output shaft andextending through at least a portion of the bell housing and the pumphousing, the main input shaft extending entirely through the power takeoff unit, where the output shaft of the prime mover and the main inputshaft are substantially coaxial; and a first pump shaft driving thefirst pump, a second pump shaft driving the second pump, a third pumpshaft driving a third pump, wherein the main input shaft is parallel toand drives the first, second and third pump shafts.
 2. A pump apparatusas set forth in claim 1, wherein the power take off unit is furthercomprised of a first pulley engageably coupled to the main input shaft,an electric clutch for engaging and disengaging the first pulley to andfrom the main input shaft and a second pulley drivingly attached to thefirst pulley by a belt, wherein the second pulley is drivingly engagedto the main input shaft by actuating the clutch.
 3. A pump apparatus asset forth in claim 2, wherein the pump apparatus further includes apower take off shaft that is fixedly coupled to the second pulley and amower deck.
 4. A pump apparatus as set forth in claim 3, wherein thepower take off shaft is positioned below the main input shaft.
 5. A pumpapparatus as set forth in claim 1, wherein the connection between theprime mover output shaft and the main input shaft is located at leastpartially within the bell housing.
 6. A pump apparatus as set forth inclaim 1, wherein the first, second and third pumps are mounted on acommon end cap.
 7. A pump apparatus as set forth in claim 6, wherein oneof the first pump, the second pump, and the third pump serves to providecharge fluid for the other two pumps.
 8. A pump apparatus as set forthin claim 1, wherein the first pump and the second pump are on generallyopposite sides of the main input shaft, the third pump is generally onone side of the first pump, the second pump and the main input shaft,and the power take off unit is generally opposite the third pump on asecond side of the first pump, the second pump and the main input shaft.9. A pump apparatus as set forth in claim 1, further comprising a fan.10. A pump apparatus as set forth in claim 9, wherein the fan is mountedon the main input shaft.
 11. A pump apparatus for use in a vehiclehaving a prime mover and a mower deck, the prime mover having an outputshaft, the pump apparatus being driven by a prime mover and the mowerdeck being driven by a motor, the pump apparatus comprising: a bellhousing attached to the prime mover; a power take off unit attached tothe bell housing; a pump housing attached to the power take off unit,the pump housing including a plurality of pumps; a main input shaftdrivingly coupled to an output shaft, which is connected to the primemover and which drives all of the pumps; the power take off unit furthercomprising a first pulley engageably coupled to the main input shaft, anelectric clutch for engaging and disengaging the first pulley to andfrom the main input shaft and a second pulley drivingly attached to thefirst pulley by a belt; and a power take off shaft that is fixedlycoupled to the second pulley and the motor.
 12. A pump apparatus as setforth in claim 11, wherein the mower deck is activated by actuating theelectric clutch.
 13. A pump apparatus as set forth in claim 12, whereinthe main input shaft is positioned above the motor.
 14. A pump apparatusas set forth in claim 11, wherein the connection between the prime moveroutput shaft and the main input shaft is located at least partiallywithin the bell housing.
 15. A pump apparatus driven by a prime mover,the pump apparatus comprising: a bell housing attached to the primemover; a pump housing attached to the prime mover and closed by an endcap; a first pump driven by a first shaft located in the pump housingand rotatably mounted on the end cap; a second pump driven by a secondshaft located in the pump housing and rotatably mounted on the end cap;a third pump driven by a third shaft and hydraulically connected to theend cap; an input shaft drivingly connected to the first shaft, thesecond shaft and the third shaft; and a power take off unit driven bythe input shaft the power take off unit comprising a clutch selectivelyengaged directly to the input shaft and an output shaft.
 16. A pumpapparatus as set forth in claim 15, wherein the power take off unit ispositioned between the bell housing and the pump housing.
 17. A pumpapparatus as set forth in claim 15, wherein the power take off unitcomprises a first pulley selectively coupled to the input shaft and asecond pulley drivingly coupled to the first pulley by a belt.
 18. Apump apparatus as set forth in claim 17, wherein the first pulley isselectively coupled by an electric clutch.
 19. A pump apparatus as setforth in claim 17, wherein the second pulley is drivingly connected to apower take off output shaft that is also drivingly connected to a mowerdeck.
 20. A pump apparatus as set forth in claim 15, further comprisinga first trunnion to control the displacement of the first pump, and asecond trunnion to control the displacement of the second pump, whereinthe first trunnion extends from the pump housing in a first directionand the second trunnion extends from the pump housing in a generallyopposite second direction.
 21. A pump apparatus as set forth in claim15, wherein the input shaft is co-linear with the output shaft.